A hierarchical storage management (HSM) is policy-based management of file backup and archiving that uses storage devices economically. The hierarchy in the HSM represents different types of storage media, such as hard drive, optical storage or magnetic tape, where each type of the storage media represents a different level of price, capacity, performance and function. For example, as a file ages in an archive without being accessed for a prolonged period of time, it can be automatically moved to a slower but less expensive type of storage. This frees up the faster storage space which was once occupied by the migrated file. However, until recently, the implementation of the HSM has been concentrated to storage systems having different types of storage media.